GB1067401A - Improvements relating to type character selection devices for high speed printers - Google Patents

Abstract

1,067,401. Electric selective signalling. INTERNATIONAL BUSINESS MACHINES CORPORATION. March 29, 1965 [April 3, 1964], No. 13165/65. Heading G4H. In a printer of the type with a moving typecarrier wherein printing is effected on equality being detected in a comparator between signals representing the character to be printed and the character currently in position, the latter signals being obtained from a rotating store, the stored representations are re-stored at different storage locations so that at the end of one revolution of the store, each character representation has been re-stored in the adjaccent storage location. After each revolution, the type-carrier is moved along one character position, the re-storing being to take account of this change. The store is a magnetic drum with three tracks read concurrently. One track holds the line of characters to be printed, the second track holds representations of the type elements in the same order as they appear on the type-carrier, and the third track holds representations of the hammer positions which are used to select the appropriate hammer on equality being detected in the comparator. The hammers are thus catered for in turn during each revolution of the store. Since the store described has less character locations per track than the total number of type elements (which comprises each character several times), the representations to be re-stored are read from one of two heads as determined by clock pulses derived from the store. A separate reading head is provided on this track to provide the comparator input.